ABSTRACT
Objective To investigate the relationship between lesion size of solitary bone cyst ( SBC) and pathological fracture of calcaneus, so as to provide references for the treatment of SBC. Methods The three dimensional (3D) finite element model of foot and ankle was established based on CT images. Four models with gradient spherical bone defects were constructed in the focal area to simulate different SBC lesion sizes, and the biomechanical characteristics of calcaneus in different gait phases were analyzed. Results With the increasement of SBC size, the kinematics of calcaneus did not change significantly, but the peak stress of calcaneus increased gradually. When the SBC size exceeded 75% of the calcaneal width, the stress in calcaneal sulcus and cortical bone below SBC increased by 1. 48 times and 7. 74 times, respectively. Conclusions The risk of pathological fracture increases when the SBC diameter exceeds 75% of the calcaneal width, and early surgical intervention should be recommended. The calcaneal sulcus and the cortex bone below SBC are stress concentration regions and can be used as important areas to evaluate pathological fractures.
ABSTRACT
Objective To analyze the biomechanical feasibility of two-point fixation by distal radius plate for the treatment of SandersⅢ calcaneal fractures. Methods The three-dimensional (3D) finite element musculoskeletal foot model was established based on CT and MRI images, which comprised bones, muscles, plantar fascia, ligaments and soft tissues. After validation, the SandersⅢ calcaneal fracture models fixed by distal radial plate (two-point fixation) and calcaneal plate (three-point fixation) were established, so as to compare the biomechanical characteristics of two calcaneal models. Results The maximum stress of the two-point fixation and three-point fixation model was 324.70 and 407.90 MPa, respectively. The maximum displacements of the two models were 2.498 and 2.541 mm, respectively. There was no significant difference in the posterior articular surface displacement between the two models. In both models, the Bohler’s angle and Gissane’s angle were within the normal range. Conclusions The two-point fixation by distal radial plate can satisfy the biomechanical stability of calcaneal fracture treatment. Compared with traditional steel plate, the two-point fixation shows the advantage of smaller surgical trauma, more uniform overall stress distribution, early weight-bearing rehabilitation after surgery, which is a novel treatment recommended for treating calcaneal fractures.
ABSTRACT
Objective:To investigate the factors affecting the outcome of surgical treatment for femoral intertrochanteric fractures.Methods:A retrospective case series study was conducted for 424 patients with intertrochanteric fractures admitted to four hospitals in Shanghai from January 2014 to December 2016. There were 200 males and 224 females, aged 45-98 years [(77.8±10.5)years]. Normal union was observed in 326 patients (normal union group), and abnormal union was founded in 98 patients including nonunion in 2 patients (abnormal union group). Data were recorded including the age, gender, injury side, AO classification, Evans-Jesen classification, thickness of femoral lateral wall, medial support, tip-apex distance, and screw position within the femoral head. Fracture healing was assessed. Univariate analysis was conducted to examine differences of the above factors between two groups, and Logistic regression was used to screen the main factors affecting fracture union. At the latest follow-up, the hip joint function was estimated according to the Oxford score system.Results:All patients were followed up for 1-3 years [(2.2±0.3)years]. Univariate analysis showed significant differences between two groups regarding the AO classification, Evans-Jesen classification, medial support, tip-apex distance, and screw position within the femoral head ( P<0.05). Multivariate regression analysis revealed that the simple fracture ( OR=1.030), medial support ( OR=0.395), tip-apex distance ≤25 mm ( OR=0.266) and inferior screw position ( OR=0.986) were significantly related to fracture union. The hip function in normal union group was (42.6±4.5)points, better than (35.4±3.2)points in abnormal union group ( P<0.05). Conclusion:The stability of intertrochanteric fracture is the most important factor for fracture union. The medial support, tip-apex distance ≤25 mm and inferior screw position are helpful to promote fracture healing and recovery of hip joint function.